He gave his brother a helping hand — and that hand was attached to a gun.

A Bronx man accused of fatally shooting his brother’s ex-roommate while the victim’s girlfriend watched in horror has been ordered held without bail after his arrest on murder charges.

Michael Rodriguez, 29, was arraigned Thursday on charges he fatally shot 22-year-old Jose Velez — roughly a month after his younger brother was charged in the young dad’s murder.

Cops say Velez was sitting in his car on Van Nest Ave. and Unionport Road in Van Nest June 19, around the corner from where Rodriguez and his brother, Thomas Bowles, live, when Bowles walked up to him and started arguing.

Minutes later, Rodriguez came up to the car and shot Velez in the chest as his girlfriend, Brigitte Ortiz, 21, watched from the passenger’s seat.

“Babe, call 911, I’m shot,” he rasped, according to Ortiz. Velez tried to drive to safety, crashing into several parked cars before coming to a stop two blocks away. He died at Jacobi Medical Center.

Cops arrested Bowles last month, and tracked down Rodriguez Wednesday.